On the Use of Morphometric Data as a Guide to Reproductive Maturity in the Ghost Crab, Ocypode ceratophthalmus (Pallas) (Brachyura, Ocypodidae)

Abstract

Morphometric data and gonadal histology of the Hawaiian Ghost Crab, Ocypode ceratophthalmus (Pallas), were compared in order to define external morphological guides to reproductive maturity. Males begin producing mature spermatozoa at a carapace width of about 27 mm, an eyestalk length of 12 mm, a copulatory pleopod length of about 11 mm, and a chelar shape index (major chelar propodus length/propodus width) of 1.5. Spermatophores are found within the posterior extensions of the testes in all males for whom these first three values exceed 33 mm, 18 mm, and 14mm, respectively; and the chelar shape index is 1.45. Females first show evidence of copulation (measured by the presence of spermatozoa in the spermathecae) and initiate vitellogenesis (production of yolk within oocytes) at carapace widths of about 33 mm and 29 mm, respectively.